Research on psychotropic drug-substance effects has often been guided by concerns with safety and, consequently, has focused on tasks that require relatively simple or intermediate levels of cognition and performance. The work place, however, contains a proportion of complex cognitive efforts that have not been adequately captured. Experimentally based knowledge of psychotropic substance effects upon performance is especially limited for white collar occupations. This research project recently began to assess the impact of psychotropic substances on a range of performance indicators that extend from memory to aspects of complex (e.g., managerial) decision making. Prior to the development of a quasi-experimental simulation with continuous control over independent variable manipulation, assessment of substance effects upon many aspects of complex task performance in white collar occupations was restricted by the absence of appropriate laboratory based measures. Reliability and validity of this simulation technique (i.e., multiple prediction of success at the work place) are excellent. The methodology collects performance data on a range of cognitive efforts, reflecting simple, intermediate and several complex aspects of task performance. The methodology has been used to measure the effects of prescription medications and alcohol. The proposed research will continue our NIDA funded research program (which was begun in March 1990). It will employ the simulation methodology (as well as several other measures) to obtain information about effects of marijuana, caffeine (treatment and withdrawal) and diazepam on simple, intermediate and complex performance. the research employs a placebo controlled double-blind cross-over design. In addition, alcohol treatment effects will be compared for males vs. females and for different stages of the female menstrual cycle. Participants will be healthy prior users of these substances, aged 21 through 45 (35 in the case of marijuana). The research was designed to help clarify the effects of the substances on (especially white collar) task performance, to elucidate the relationship between blood levels and complex performance, to determine the effects of substance dosage upon complex performance and to obtain information on potential parallel substance effects upon different kinds (or levels) of performance that requires diverse cognitive efforts. The obtained results will provide previously unavailable information about substance effects upon task characteristics typically performed by the white collar work force. Obtained data should also be useful for public relations campaigns that are intended to dissuade white collar employees from using psychotropic substances.